This study will test whether men are similar to or different from women in an acute alcohol administration study. Subjects will receive placebo and one dose of alcohol. Dependent measures will include blook alcohol, ovarian hormone concentrations, B-endorphin levels and the subjective and behavioral responses. Women will be tested at two hormonally distinct phases of their menstrual cycle; follicular, when circulating ovarian hormones are relatively low; and luteal, when progesterone levels are expected to be high and estradiol levels are expected to be moderate. Recent evidence suggest that sex steroids and alcohol may share cellular localization with endogenous response or the GABA(A) mediated response to alcohol (Jirikowski et al, 1986; Grant, 1994). In non-human primates, monkeys were more sensitive to the discriminative stimulus effects of ethanol during the luteal phase compared to the follicular phase of the menstrual cycle (Grant et al, 1997). These findings suggest that menstrual cycle phase may alter sensitivity to ethanol in humans.